Refrigerating apparatus



REFRIGERATING APPARATUS Filed July 2, 1955 INVENTOR. James W. Jacobs FQKM.

His Attorney.

2,716,857 Patented Sept. 6, 1955 ice REFRIGERATING APPARATUS James W. Jacobs, Dayton, Ohio, assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Application July 2, 1953, Serial N 0. 365,592

9 Claims. (Cl. 62-4) This invention relates to refrigeration and particularly to a refrigerating system wherein the evaporator thereof is kept free of frost or ice.

Heretofore it has required a considerable amount of time to defrost the evaporator of a refrigerating system associated with and utilized to cool the interior of a refrigerator cabinet. I am aware of the fact that others have provided means to circulate hot refrigerant gas in a closed refrigerating system through the evaporator thereof and/or have associated electric heaters with the evaporator for heating the same in order to reduce the time required to defrost an evaporator of a refrigerating system. These expedients in addition to rendering a refrigerating system inefficient also complicate the same and increase their manufacturing cost since special additional instruments or devices are required as elements in a refrigerating apparatus. I contemplate the provision of a refrigerating system the evaporator of which can be quickly defrosted without applying heat of the system thereto and without employing artificial heating means whereby the efficiency of the system is not impaired and its cost is not materially increased.

An object of my invention is to provide an improved refrigerating apparatus of low manufacturing cost.

Another object of my invention is to provide means in a closed refrigerating system whereby liquid refrigerant can be removed from the evaporator thereof employed to cool a compartment in a refrigerator cabinet so that warming of the evaporator will be hastened and frost or ice accumulated thereon will more rapidly melt therefrom.

A further object of my invention is to provide a method of controlling a closed refrigerating system for removing frost or ice from the evaporator thereof after each operating or refrigerating producing cycle of the refrigerant translating device of the system which eliminates the necessity of adding special equipment to the apparatus for effecting such defrosting.

In carrying out the foregoing objects it is a still further and more specific object of my invention to remove liquid refrigerant from an evaporator of a refrigerating system to a non-refrigerated insulated flash back chamber in the system when the refrigerant translating device thereof stops operating to thereby permit the temperature of the evaporator to more rapidly increase above 32 F. to cause frost accumulated thereon to melt therefrom prior to a subsequent operating or refrigerating producing cycle of the refrigerant translating device.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

The single figure in the drawing is a vertical sectional view through a refrigerator cabinet embodying my invention and showing a refrigerating system diagrammatically associated therewith.

Referring now to the drawing a refrigerator cabinet, generally represented by the reference character 10, includes an outer shell or housing 11 and a metal liner 12 spaced therefrom and forming walls of a single food storage compartment 14 within the cabinet. Compartment l4'may have a plurality of vertically spaced apart shelves (not shown) disposed therein as is conventional in refrigerator cabinets. Any suitable or conventional insulating material 15 is disposed between outer housing 11 and liner 12 of the cabinet. The compartment 14 has an access opening at the front of cabinet 10 normally closed by a door (not shown). Outer shell or housing 11 extends downwardly beyond the bottom wall of food compartment 14 to provide a machine or mechanism compartment in the lower portion of cabinet 10 normally closed by a removable cover 16. A closed refrigerating system is associated with cabinet 10 and includes a non-refrigerating receptacle 21 forming a flash back chamber, for a purpose to be hereinafter described, located in the top wall of the cabinet. This receptacle or flash back chamber 21 is disposed in the space between the cabinet outer walls or housing 11 and liner 12 and is completely embedded in or surrounded by the insulating material 15. Thus chamber or receptacle 21 is isolated from ambient temperatures about the same. Chamber 21 is connected to a single evaporator 22 of the closed refrigerating system by a trapping means or conduit 23 and is preferably elongated and of such capacity as to receive and trap therein substantially all liquid refrigerant contained in the evaporator 22. Evaporator 22 is disposed within compartment 14 for chilling the interior thereof and causing air therein to circuiate about food products adapted to be stored in this compartment. The evaporator 22 is preferably of the sheet metal plate type mounted in spaced relation to the rear wall of compartment 14 in any suitable manner. Such evaporators are now well known to those skilled in the art and may be formed by superimposing an embossed metal sheet upon another metal sheet and welding or brazing the sheets together. The embossations in the one metal sheet form refrigerant evaporating passages between the secured together sheets or plates. A trough 17 is disposed below evaporator 22 and has an outlet spout 18 directed toward or against the rear wall of compartment 14. A drain pipe 19 is secured to the bottom wall of compartment 14 and extends through the insulation 15 into the machine compartment in the lower portion of cabinet 10.

In the present disclosure one end of a passage 24, between the metal sheets of the plate-like evaporator 22, is connected to conduit 23 and has its other end communieating with a refrigerant accumulator passage 25. A refrigerant outlet passage 26 extends from the accumulator 25 over to a side edge of evaporator 22. The refrigerating system also includes a refrigerant translating device which is usually located in the machine compartment of cabinet 10 normally closed by the cover 16. This refrigerant translating device comprises a condenser 27 and a closed casing or unit 28 containing an electric motor and a compressor directly connected thereto and adapted to be driven thereby. A conduit 29 connects unit 28 to condenser 27 and a small diametered or capillary tube 31 connects condenser 27 to the non-refrigerating receptacle or flash back chamber 21. Another conduit 32 connects the compressor within unit 28 to the outlet passage 26 of evaporator 22. Means is provided for controlling the starting and stopping of the motor and consequently the compressor within unit 28. This control means is directly responsive to temperatures of evaporator 22 and includes a thermostatic snap-acting electric switch 34. A

The bellows 36, tube 37 and bulb 38 are sealed to one another and contain a predetermined charge of a suitable volatile fluid. The movable arm of switch 34 is adapted to actuate a contact 41 into or out of engagement with a stationary contact 42 interposed in one of the wires 43 or 44 of the electric supply means leading to and from the unit 28. Bulb 38 of the power unit of switch 34 is mounted in thermal contact with evaporator 22 and is directly responsive to changes in temperature thereof.

In order to augment evaporator 22 in its cooling of the interior of the food storage compartment 14 and to provide means, in addition to the air in compartment 14, for transferring heat to evaporator 22 I employ a second refrigerating system. This second refrigerating system is in the form of a secondary closed circuit containing a suitable volatile refrigerant. The secondary refrigerating system includes a refrigerant evaporating portion in the form of a conduit 46 secured to and extending over the outer surface of liner 12 forming the walls of compartment 14. The secondary refrigerating system also includes a refrigerant condensing portion in the form of a receiver 47 secured, in an inclined manner, in intimate thermal contact with the back of the plate-like evaporator 22 of the primary refrigerating system. One end of conduit 46 extends through the rear wall of compartment 14 and is connected to the uppermost part of receivercondenser 47. The other end of the refrigerant evaporating conduit portion 46 of the secondary refrigerating system also extends through the rear wall of compartment 14 and is connected with a lower part of receiver-condenser 47. Liquid refrigerant in the closed secondary system or circuit removes heat from walls of compartment 14 and vaporizes in conduit 46 to thereby rise therein whereupon it enters the condenser-receiver 47 and carries or transfers this heat to the evaporator 22 of the primary refrigerating system. The lower temperature of evaporator 22 causes the vaporized refrigerant in condenser-receiver 47 to again condense or liquefy and be fed back into the evaporating coil 46. While this secondary refrigerating system is not essential to the present invention it has been found to be desirable for aiding in the cooling of compartment 14 and in providing means for at all times applying heat to the primary evaporator 22.

Thermostatic switch 34 is set to both open and close contacts 41 and 42 to start and stop the electric motor and consequently the compressor in unit 28 at predetermined temperature limits of the evaporator 22. For example switch 34 will close contacts 41 and 42 to energize and start the motor in operation in response to a temperature of evaporator 22 of approximately 36 F. above zero. Switch 34 will open contacts 41 and 42 to deenergize and stop operation of the motor and consequently the compressor of unit 28 in response to a temperature of evaporator 22 of approximately F. The running or refrigerating producing cycle of the refrigerant translating device of the closed primary refrigerating system causes moisture in the air within food compartment 14 to be removed therefrom and deposited on surfaces of evaporator 22 in the form of frost or ice. When the wires 43 and 44 are connected to a source of electric current supply the temperature of evaporator 22 and consequently bulb 38 will cause the power unit or bellows 36 of switch 34 to expand and actuate the switch to close contacts 41 and 42 for completing the electric circuit to the motor in casing or unit 28.. Operation of the motor drives the compressor in unit 28 and this compressor withdraws gaseous refrigerant from evaporator 22 by way of the conduit 32. The suction of the compressor causes vaporization of the refrigerant in evaporator 22 to thereby remove heat from the food storage compartment 14. This operation of the compressor compresses gaseous refrigerant entering the same and forwards the compressed refrigerant to condenser 27, by way of conduit 29, wherein it is cooled and condensed to a liquid state in any suitable or well known manner. Liquid refrigerant is directed to the insulated non-refrigerating flash back receptacle or chamber 21 by the pressure reducing means or capillary tube 31. The trapping conduit 23 picks up liquid refrigerant from chamber 21 and directs the same into the passage 24 of the plate-like sheet metal evaporator 22 wherein it vaporizes and is again returned to the compressor of the refrigerating system. The accumulator 25 insures that only vaporized or gaseous refrigerant enters conduit 32 for return to the compressor and also serves as a chamber wherein the pressure of gaseous refrigerant may be utilized to expel liquid refrigerant from the evaporator 22 into the chamber 21, in advance thereof, when the motor and compressor of unit 28 stops operating. During the refrigeration producing cycle of the refrigerating system, to bring the temperature of evaporator 22 down to approximately 0 F., frost accumulates on the surfaces of this evaporator. The refrigeration producing cycle of the primary refrigerating system also lowers the temperature of the refrigerant condensing portion 47 of the secondary refrigerating system to render this system or circuit functionable to cause evaporation of refrigerant in the conduit 46 for augmenting primary evaporator 22 in cooling compartment 14.

When the temperature of evaporator 22 reaches its low limit of 0 F. thermal bulb 38 responsive thereto will actuate switch 34 to open the contacts 41 and 42 and stop operation of the motor and compressor. By virtue of the fact that in the present refrigerator no provision is made to freeze water into ice blocks there is no substantial amount of cold holdover associated with evaporator 22 and consequently its temperature will immediately increase when the motor and compressor stops operating. This temperature increase of evaporator 22 is augmented by heat supplied thereto by the condensing portion 47 of the secondary refrigerating system. Thus refrigerant in the accumulator 25 continues to evaporate and the pressure created therein by the vaporizing refrigerant causes liquid refrigerant in the bottom of accumulator 25 and in passage 24 of evaporator 22 to be forced or pushed back out of passage 24 into the insulated non-refrigerating fiash back chamber 21 by way of conduit 23. This liquid refrigerant is stored or trapped in chamber 21, by the trapping conduit 23, and is maintained in readiness to be re-fed into evaporator 22 when the motor and compressor are again started in operation. Since substantially all liquid refrigerant is in this manner removed from evaporator 22 its temperature will rise rapidly above 32 F. and cause frost or ice accumulated thereon, during the running or refrigerating cycle of the refrigerating system, to be melted therefrom. The defrosting or removal of frost or ice from evaporator 22 occurs while the temperature of this evaporator is increasing from 32 F. to approximately 36 F. at which point the thermal bulb 38 responds to again start operation of the motor and compressor of the refrigerating system. In other words removal of frost from evaporator 22 is effected prior to the time this evaporator reaches the high temperature at which the thermostatic means will start the motor of unit 28.

Water resulting from defrosting the evaporator 22 will flow therefrom into trough 17 and outwardly thereof by way of the spout 18 onto the rear wall of compartment 14. The water flows down along the rear food compartment wall onto its bottom wall and thence into the drain pipe 19 from where it may be deposited in a moisture removing or evaporating receptacle located in the machine compartment of the refrigerator cabinet 10.

By virtue of the flash back chamber 21 in the present refrigerating system, which receives substantially all liquid refrigerant contained in evaporator 22, defrosting of evaporator 22 occurs rapidly and without permitting the temperature within the food storage compartment 14 from increasing to the point that would be detrimental to the proper preservation of food products stored therein. Since the evaporator 22 is defrosted at the end of each refrigerating or running cycle of the refrigerating system not much frost accumulates thereon and the period of time during which the temperature of evaporator 22 increases from 32 F. to 36 F. is ample to insure complete defrosting of the evaporator. Removal of frost from the evaporator in the manner herein disclosed together with the fact that no artificial heating means or heated refrigerant in the system is employed materially increases the efficiency of the refrigerating system. Thus, from the foregoing it should be apparent that, I have provided an improved refrigerating apparatus wherein no timed or other types of instruments or devices are required to effect defrosting of the evaporator of the primary refrigerating system and a practical apparatus of low manufacturing cost is therefore obtained.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. A refrigerating apparatus comprising in combination, a cabinet, said cabinet having an outer housing, an inner liner spaced from said housing and forming Walls of a food storage compartment within said cabinet, insulating material in the space between said housing and said liner, a closed refrigerating system associated with said cabinet, said system including a non-refrigerating flash back chamber, an evaporator and a refrigerant liquefying device, said device comprising a motor and a compressor driven thereby for circulating refrigerant through said flash back chamber and said evaporator in succession, said non-refrigerating flash back chamber being located in the space between said cabinet outer housing and said liner and completely surrounded by the insulating material therein, said evaporator being located within said compartment for cooling air therein and adapted to have frost accumulated thereon, thermostatic means responsive to a temperature of said evaporator below freezing for stopping said motor, said thermostatic means also being responsive to a temperature of said evaporator above freezing for starting said motor, and said non-refrigerating flash back chamber receiving liquid refrigerant from said evaporator automatically in response to said thermostatic means stopping said motor for permitting the temperature of said evaporator to rise above 32 F. to effect removal of frost therefrom' prior to reaching the temperature at which said thermostatic means will start said motor.

2. A refrigerating apparatus comprising in combination, a cabinet, said cabinet having an outer housing, an inner liner spaced from said housing and forming walls of a food storage compartment within said cabinet, insulating material in the space between said housing and said liner, a closed refrigerating system associated with said cabinet, said system including a non-refrigerating flash back chamber, an evaporator and a refrigerant liquefying device, said device comprising a motor and a compressor driven thereby for circulating refrigerant through said flash back chamber and said evaporator in succession, said non-refrigerating flash back chamber being located in the space between said cabinet outer housing and said liner and completely surrounded by the insulating material therein, said evaporator being located within said compartment for cooling air therein and adapted to have frost accumulated thereon, thermostatic means responsive to a temperature of said evaporator below freezing for stopping said motor, said thermostatic means also being responsive to a temperature of said evaporator above freezing for starting said motor, said non-refrigerating flash back chamber receiving liquid refrigerant from said evaporator automatically in response to said thermostatic means stopping said motor for permitting the temperature of said evaporator to rise above 32 F. to effect removal of frost therefrom prior to reaching the temperature at which said thermostatic means will start said motor, and a secondary refrigerating system having a refrigerant evaporating portion augmenting said evaporator in cooling said compartment and a refrigerant condensing portion in thermal contact with said evaporator for applying heat thereto when said motor stops.

3. In a refrigerating system, refrigerant liquefying means, a single evaporator, means for supplying liquid refrigerant from said liquefying means to said evaporator including a pressure reducing means and a non-refrigerating flash back chamber between said pressure reducing means and said single evaporator, means responsive to refrigeration requirements for starting and stopping said refrigerant liquefying means to cause said single evaporator to alternately produce a temperature below 32 F. and above 32 F., and means rendered effective automatically in response to stopping said refrigerant liquefying means for expelling liquid refrigerant from said evaporator and trapping the same in said flash back chamber.

4. In a refrigerating system, refrigerant liquefying means, a single evaporator, means for supplying liquid refrigerant from said liquefying means to said evaporator including a pressure reducing means and a nonrefrigerating flash back chamber between said pressure reducing means and said single evaporator, insulating material completely surrounding said flash back chamber, means responsive to refrigeration requirements for starting and stopping said refrigerant liquefying means to cause said single evaporator to alternately produce a temperature below 32 F. and above 32 F, and said single evaporator comprising a sheet metal plate having an accumulator formed therein so constructed and arranged as to force liquid refrigerant from said evaporator into said insulated flash back chamber automatically in response to stoppage of said refrigerant liquefying means and vaporization of a portion of the liquid in said single evaporator.

5. In a refrigerating system, refrigerant liquefying means, a single evaporator, means for supplying liquid refrigerant from said liquefying means to said evaporator including a pressure reducing means and a nonefrigerat ing flash back chamber between said pressure reducing means and said single evaporator, insulating material completely surrounding said flash back chamber, means responsive to refrigeration requirements for starting and stopping said refrigerant liquefying means to cause said single evaporator to alternately produce a temperature below 32 F. and above 32 F., said single evaporator comprising a sheet metal plate having an accumulator formed therein so constructed and arranged as to force liquid refrigerant from said evaporator into said insulated flash back chamber automatically in response to stoppage of said refrigerant liquefying means and vaporization of a portion of the liquid in said evaporator, and a secondary refrigerating system having a refrigerant evaporating portion and a refrigerant condensing portion in thermal contact with said single plate evaporator for applying heat thereto when said refrigerant liquefying means stops.

6. A refrigerating apparatus comprising in combination, a cabinet, said cabinet having an outer housing, an inner liner spaced from said housing and forming walls of a food storage compartment within said cabinet, insulating material in the space between said housing and said liner, a closed refrigerating system associated with said cabinet, said system including a non-refrigerating flash back chamber, an evaporator and a refrigerant liquefying device, said device comprising a motor and a compressor driven thereby for circulating refrigerant through said flash back chamber and said evaporator in succession, said non-refrigerating flash back chamber being located above said evaporator in the space between said cabinet outer housing and said liner and completely surrounded by the insulating material therein, said flash back chamber being of a capacity adapted to receiver substantially all liquid refrigerant contained in said evaporator, said evaporator being located within said compartment for cooling air therein and adapted to have frost accumulated thereon, thermostatic means directly responsive to a temperature of said evaporator below freezing for stopping said motor, said thermostatic means also being directly responsive to a temperature of said evaporator above freezing for starting said motor, and said non-refrigerating insulated flash back chamber receiving liquid refrigerant from said evaporator automatically in response to said thermostatic means stopping said motor for permitting the temperature of said evaporator to rise above 32 F. to effect removal of frost therefrom prior to reaching the temperature at which said thermostatic means will start said motor.

7. A refrigerating apparatus comprising in combination, a cabinet, said cabinet having an outer housing, an inner liner spaced from said housing and forming walls of a food storage compartment within said cabinet, insulating material in the space between said housing and said liner, a closed refrigerating system associated with said cabinet, said system including a non-refrigerating flash back chamber, an evaporator and a refrigerant liquefying device, said device comprising a motor and a compressor driven thereby for circulating refrigerant through said flash back chamber and said evaporator in succession, said non-refrigerating flash back chamber being located above said evaporator in the space between said cabinet outer housing and said liner and completely surrounded by the insulating material therein, said flash back chamber being of a capacity adapted to receive substantially all liquid refrigerant contained in said evaporator, said evaporator being located within said compartment for cooling air therein and adapted to have frost accumulated thereon, thermostatic means directly responsive to a temperature of said evaporator below freezing for stopping said motor, said thermostatic means also being directly responsive to a temperature of said evaporator above freezing for starting said motor, said non-refrigerating insulated flash back chamber receiving liquid refrigerant from said evaporator automatically in response to said thermostatic means stopping said motor for permitting the temperature of said evaporator to rise above 32 F. to effect removal of frost therefrom prior to reaching the temperature at which said thermostatic means will start said motor, and a secondary refrigerating system having a refrigerant evaporating portion augmenting said evaporator in cooling said compartment and a refrigerant condensing portion in thermal contact with said evaporator for applying heat thereto when said motor stops.

8. In a closed refrigerating system having a single evaporator, refrigerant liquefying means and means for supplying liquid refrigerant from said liquefying means to said evaporator, said last named means including a pressure reducing means, a non-refrigerating flash back chamber interposed in said closed system intermediate said single evaporator and said pressure reducing means, insulating material completely surrounding said flash back chamber to isolate the same from ambient temperatures thereabout, means responsive to refrigeration requirements of said single evaporator for starting and stopping said refrigerant liquifying means to cause said single evaporator to alternately produce a temperature below 32 F. and above 32 F., and means rendered effective automatically in response to stopping said refrigerant liquefying means for expelling liquid refrigerant from said evaporator and trapping the same in said insulated flash back chamber.

9. In a closed refrigerating system having a single evaporator, refrigerant liquefying means and means for supplying liquid refrigerant from said liquefying means to said evaporator, said last named means including a pressure reducing means, a non-refrigerating flash back chamber interposed in said closed system intermediate said single evaporator and said pressure reducing means, insulating material completely surrounding said flash back chamber to isolate the same from ambient temperatures thereabout, thermostatic means directly responsive to a temperature of said single evaporator below freezing for stopping said refrigerant liquefying means, said thermostatic means also being directly responsive to a temperature of said single evaporator above freezing for starting said refrigerant liquefying means, and said insulated non-refrigerating flash back chamber automatically receiving liquid refrigerant from said single evaporator in response to said thermostatic means stopping said refrigerant liquefying means for permitting the temperature of said evaporator to rise above 32 F.

References Cited in the file of this patent UNITED STATES PATENTS 2,036,756 Hull Apr. 7, 1936 2,426,578 Tobey Aug. 26, 1947 2,455,850 Atchison Dec. 7, 1948 2,492,648 McCloy Dec. 27, 1949 2,492,970 Curry Jan. 3, 1950 2,586,853 Morton Feb. 26, 1952 2,665,558 Fiene Jan. 12, 1954 

